Twilight should mostly work out of the box. Please make sure you enable Device settings > Location from network. In this case Twilight will automatically detect your sunset and sunrise time and synchronize your screen tint with the sun.
In case you are a shift worker, night time worker, live close to the pole or in general your schedule is irregular and not connected with the sun cycle you may want to select other Filter times and Sun. You may choose to use filter times based on your alarm time, custom times or use Filter times: always and control Twilight manually using pause and resume.
The default intensity and temperature settings are a compromise between blue light filtering and appearance. To achieve better blue light filtering consider using higher intensity over 60% and combine it with a non-zero dim. The more intensity and dim you use the more blue light gets filtered but also the less contrast of your screen.
Ideal color temperature is 1000K which maximizes contrast and minimizes blue and green. Adding more temperature may be softer on the eyes but may add green which according to some studies may also have effect on melatonin.
Automation of Twilight with Tasker/Locale/Llama etc. (by Niki)
While there is no dedicated Tasker or Locale plugin for Twilight, it is still possible to automate it using intents.
For example, you can manually schedule when Twilight becomes active or inactive, not only based on the rough location, time or sunset.
Instead you could add certain conditions such as Cell Near, Wifi or Power Connected.
The intents must be addressed as target Service to the service class com.urbandroid.lux.TwilightService in the package com.urbandroid.lux. The commands are supplied as extras. The extras are of type string and the value can be set to an arbitrary value.
However, it is recommended to set the value to the same name as the extras name.
The supported list of extras are:
* profile = <profile name>
The correct configuration is as follows:Action: [empty]